Affiliation: | 1. Division of Organic Chemistry, Chemical Center, University of Lund, P.O.B. 740, S-220 07 Lund 7, Sweden;2. I.P.S.O.I., Université Aix Marseille III, St. Jérome, 13013 Marseille, France;3. Ecole Normale Supérieure, 14 Bd de la Liberté, Le Bardo, Tunis, Tunisie |